The present disclosure generally relates to subterranean treatment fluids and, more specifically, to methods for quantifying nitrogen-containing polymers and other nitrogen-containing compounds in treatment fluids.
Treatment fluids may be used in a variety of subterranean treatment operations. Such treatment operations can include, without limitation, drilling operations, stimulation operations, production operations, remediation operations, sand control treatments, and the like. As used herein, the terms “treat,” “treatment,” “treating,” and grammatical equivalents thereof refer to any subterranean operation that uses a fluid in conjunction with achieving a desired function and/or for a desired purpose. Use of these terms does not imply any particular action by the treatment fluid or a component thereof, unless otherwise specified herein. More specific examples of illustrative treatment fluids can include, for example, drilling fluids, fracturing fluids, gravel packing fluids, acidizing fluids, conformance fluids, scale dissolution and removal fluids, diverting fluids, and the like.
A drilling fluid or drilling mud is a designed fluid intended for circulation through a wellbore to facilitate a drilling operation. Functions of a drilling fluid can include, without limitation, removing drill cuttings from the wellbore, cooling and lubricating the drill bit, aiding in the support of the drill pipe and the drill bit, and forming a hydrostatic head to maintain integrity of the wellbore walls and/or to prevent blowouts from occurring. Drilling fluids may be water-based or oil-based and may sometimes be in the form of an emulsion.
One or more polymers may be included in a drilling fluid in order to facilitate the above-described drilling fluid functions. The included polymer(s) can be soluble or insoluble (e.g., suspended or emulsified) in the continuous phase of the drilling fluid. When the continuous phase of the drilling fluid is water-based, for instance, acrylamide polymers and copolymers are commonly used. Although acrylamide polymers and copolymers represent one class of polymers that may be used in drilling fluids, other types of nitrogen-containing polymers, possibly having different solubility properties, may be present instead. For example, polyamides and nitrile-containing polymers may be insoluble in the continuous phase of a water-based drilling fluid.
Polymers may be used in other types of treatment fluids as well. Illustrative functions of polymers, particularly nitrogen-containing polymers, in other types of treatment fluids include, for example, viscosification, conformance control, permeability modification or relative permeability modification, friction control, scale inhibition, and the like.
Because they may markedly impact the properties and functionality of drilling fluids and other types of treatment fluids, it is often desirable to know with some certainty the quantity of a polymer additive that is present in a drilling fluid or other type of treatment fluid sample at a given point in time. However, polymer assays can be non-straightforward and time-consuming depending on the sample characteristics and the particular type of polymer that is present. In many instances, highly specialized and labor-intensive analyses may be needed for certain types of polymers and/or to accommodate the particular characteristics of a given fluid sample.
Because acrylamide polymers and copolymers enjoy widespread use in the oilfield, a number of wet-chemical analyses have been developed for these types of polymers. Illustrative techniques for assaying water-soluble acrylamide polymers and copolymers include precipitating a tin complex of the polymer and weighing the tin complex following centrifugation, or conducting a hydrolysis of the polymer under mild alkaline conditions. These analyses are not considered to be amenable to polymers in insoluble form, nor are they considered to be broadly applicable to other types of polymers that may be present in treatment fluids. The analyses commonly used for acrylamide polymers and copolymers also require equipment and skills that are not routinely present at a job site. Furthermore, considerable processing time and labor may be involved in conventional polymer analyses, potentially providing untimely and economically unfavorable support of an ongoing treatment operation.